Process of manufacture of phosphatic fertilizers



Patented May' 23, 1933 UNITED STATES cmnns LEU, on BEX, SWITZERLAND, ASSIGNOR T0 soorErE ANONYME POUR LE' .rmurnmmrr DES Humans ALUMINO-POTASSIQUES, or LAUSANNE, swrrzna- PATENT oFF-ica LAND, A CORPORATION OF SWITZERLAND raocnss or mauurnc'man or PEOSPHATIG rnn'rimznas Ho Drawing. Application filed February 12, 1931, Serial No. 515,411, and in Switzerland February 17,1930.

The fertilizer in view is a mixtureof calcium phosphates, partially soluble in water, partially soluble in the ammonium citrate, and partially soluble in citric acid. It is prepared by melting natural tricalcium phosphate and in running the melted mass into an aqueous solution ofphosphoric acid, the water of which is thus partially volatilized.

The melting of tricalcium phosphate may be effected in an electric oven for example, but in being careful not to reduce the phosphoric acid and thus produce phosphide of calcium. 7

The quantities of natural phosphate and phosphoric acid to be employed depend upon the ratio it is desired to obtain, in the finished product, between the phosphate soluble 1n water, the phosphate soluble in ammonium citrate and the phosphate soluble in citric acid. The former are approximately calculated by using the following theoretical equations:

- tricalcium 3CaH (P04) 2 nH O monocalcium H.120. ca. (P0,) 2 nH O= tricalcium 3CaHPO, nI-I O dicalcium 3H,,PO C a PO 2 nH O tr ca c um QCaH, (P0 2 +gaHPO, nH O monocalcium calcium I signature.

acid) which natural phosphates always contain.

As it may be seen, the'ratio between the monocalcium phosphateand the phosphates soluble in citrate and in the citric acid of the finished product may vary from nearly 0 to about 1 according to the choiceof the manufacturer.

The same result'may be obtained if the phosphoric acid solution is first fortified with a salt of phosphoric acid which then remains mixed in the product obtained.

I claim:

1. Process of preparation of phosphatic fertilizers essentially constituted by a mix: ture of monocalcium phosphate, dicalcium phosphate and complex phosphates soluble 1n citric acid, this process consisting in running the suitable quantity of natural'phosphate of calcium in fusion into a phosphoric acid solution. v,

2. Process of preparation of phosphatic fertilizers essentially constituted by a mixture of monocalcium phosphate, dicalcium I phosphate-and complex phosphates soluble in citric acid, comprising melting natural tricalcium phosphate, running the melted mass '1 into an aqueous solution of phosphoric acid,

dryinlg and crushing the obtained product.

- 3. rocess, of preparing phosphatic fertilizers essentially constituted by a mixture of monocalcium phosphate, dicalcium hosphate and complex phosphates solub e in citric acid, comprising melting natural tricalcium phosphate, running the melted mass into an aqueous solution of phosphoric acid, which solution has first been fortified with a salt of phosphoric acid.

In testimony whereof I have aflixed my CHARLES (LEU.

In fact, when it is proposed to obtain pure dicalcium phosphate, a small proportion of monocalcium and a greater proportion of complex phosphates .soluble in citric acid, are

always found in the final product. I i

It is necessary to take intoconsideration "in the. calculation the calcium oxide (combinedWith weaker acids than phosphoric 

